Thermoresponsive device



y 1945. A. STOCKSTROM 2,376,631

- THERMO-RESPONSIVE DEVICE Original Filed Oct. 20, 1941 2 Sheets-Sheet 1IQ glmflnnentor Gttomeg S y 1945- A. STOCKSTROM 2,376,631

THERMO-RESPONSIVE DEVICE Original Filed 001:. 20, 1941 2 Sheets-Sheet 22 E r I Gttomeg s Patented May 22, 1945 TEERMORESPONSIVE DEVICE ArthurStockstrom, St. Louis, Mo., assignor to American Stove Company, St.Louis, Mo., a corporation of New Jersey Original application October 20,1941, Serial No. 415,841. Divided and this application August 21, 1943,Serial No. 499,535

2 Claims.

The present invention is a division of applicant's copending applicationSerial No. 415,841 entitled Thermo-responsive devices, and relates tothermo-responsive devices and to such class of devices generally ratherthan specifically, but by reason of the invention being particularlysuited for and eflicient in connection with gas ranges and constitutinga decided improvement in thermostatic heat regulators and fuel controldevices for gas ranges the invention is illustrated in the accompanyingdrawings in connection with gas ranges and described specifically inrespect to its use on gas ranges.

It is to be understood however that the invention is not limited for useon gas ranges inasmuch as the invention provides a means of thermostaticresponse to the heat generated by any type of device and particularlyfor response to high temperatures.

Most-gas cooking ranges today are provided with automatic thermostatictemperature control for the ovens of the range and likewise such rangesfor a large part are-provided with automatic main burner ignition whichrequires the provision of thermostatically operated safety fuel controlvalves, and in the accompanying drawings a thermostatically operatedoven heat control is illustrated as is likewise a thermostaticallyoperated safety valve. In connection with both of said devices they areof the so-called liquid type" in that a liquid constitutes the thermalresponse medium which operates the mechanical parts of the devices toaccomplish the desired result.

Thermostatically operated heat control devices as well as safety valvesof theliquid type can and do vary widely in construction and hence theaccompanying drawings are to be considered as merely illustrative ofconstruction and not in any sense to constitute a limitation of theinvention.

As a consequence of the foregoing the present invention residesprimarily in the particular liquid utilized in devices of theaforementioned character as the thermal responsive means for actuatingthe devices.

Devices of the character described have proven far from satisfactory inthat the thermo-responsive fluids which have been utilized hasnecessitated or confined the satisfactory use of these devices totemperatures not in excess of 550 F. while it is necessary, as willhereinafter appear, to deal with and control with'temperatures which arein excess of 650 F.

As a general statement it can be said that devices of the character heredealt with have in the past been objectionable, inefflcient and notcomso mercially adaptable for use in connection with high temperaturework because the thermo-responsive medium of the devices has had too lowa decomposition temperature; has had a low boiling point; has had highvapor pressure and high cost; has so greatly restricted the operatingtemperatures of gas ranges as to curtail undesirably the functions ofthe ranges; along with other specific objections as will hereinafterappear.

With devices 'of the character described as heretofore known and in use,the thermo-responsive liquid of the devices are quite apt to andfrequently do break down or decompose and render the devices inoperativeif the thermo-responsive medium is subjected to a temperature in excessof 650 F. It has been found that in range ovens, particularly in rangesused in hotels, restaurants and the like, temperatures in excess of 650F. are often necessary in order to braise and sear meats.

In many ranges, particularly domestic ranges, a single oven and a singleburner, which burner is under the control of the baking oven temperatureregulator, are utilized for both baking and broiling operations. Thetemperature necessary to be reached for successful and proper broilingoperationis much higher than that utilized in baking operations butsince the thermo-responsive element of the control device is in thecombination bakin and broiling oven and responsive to the heat generatedtherein it is often difilcult if not impossible, with control devicesutilizing any of the liquid thermo-responsive mediums heretofore in use,to reach. the desired broiling temperature or if it is reached the lifeof the temperature control device is shortened or destroyed by theintense heat to which the thermo-responsive medium of the baking oventemperai wse control device is subjected. in many instaz es it isimpossible to reach the desired broiling tempera ture because thethermo-responsive medium sets up a throttling action on the gas flowingto the combined broiler and baking burner.

The lives of devices of the character here being discussed as made inthe past and at the present time are also jeopardized in another mannerand which when it occurs will in the majority of instances completelydestroy the devices by rendering them so inaccurate as to amount torendering them inoperative. In the manufacture of ranges the heatcontrol devices are calibrated at the factory and if for any reasonduring use the devices become inaccurate they are re-calibrated byservice men. Either at the factory or by the service mens carelessnessor mistake in setting a calibration by over-adjustment will permit therange burner or burners to generate in the range ovens a temperaturemuch in excess of 650 degrees and when this occurs the value of thethermo controlled devices are destroyed.

It is therefore the primary object of the present invention to provide athermo-responsive fluid which will stand temperatures greatly in excessof 650 degrees and by so doing obviate the recited short-comings ofliquid heat control devices as now known and used.

In providing such a thermo-responsive liquid for use in heat regulatorsfor high temperature use, this liquid has certain attributes not true ofthermo-responsive liquids as heretofore known. These attributes compriseextremely high boiling points and extremely low melting points takentogether with the ability to withstand high temperatures withoutbreaking down or decomposing, all of which assures accuracy anddurability of the devices over a greater temperature range than has beenpossible with thermo-operated devices in the past.

In the drawings, which are illustrative of the two specific applicationsof the inventive thought:

Fig. 1 is a sectional view through an automatic thermo-responsive heatregulator embodying the present invention.

Fig. 2 is a view. partly in section, illustrating the gas by-pass andillustrating the temperature setting dial of the device.

Fig. 3 is a sectional view of a thermo-operated fuel safety controlvalve and its application to a gas range.

Fig. 4 is a front view of a heat control dial for the present hightemperature device.

Fig. 5 is a heat control dial such as found on present temperature heatcontrol devices.

It being desirable in domestic ranges and particularly combination ovenand broiler ranges and in respect to safety valves to have athermostatically controlled temperature range greater than thehereinbefore normal range of 250 R4550 F., I provide for this byutilizing in the thermo-responsive devices a thermo-responsive medium orliquid of the organo-silicon group of compounds and of this grouptetraphenoxysilane known as tetraphenyl silicate, is particularly wellsuited and adapted to accomplish the new and improved results.

In devices heretofore known and in use it has been common practice toutilize diphenyl compounds as a heat responsive medium but these havethe undesirable characteristic of boiling at about 650 F. and ifsubjected to a temperature in excess of 650 degrees there is gravedanger of these compounds breaking down to the extent that the devicewith which they are used becomes inoperative. Tetraphenoxysilane remainsliquid down to 120 F. and base. boiling point of between 770" F. and 778F. The attributes of this material is such that when it is used as thethermo-responsive medium in a thermo-responsive device said device canbe safely used to accurately operate at much higher temperatures thanhave such devices in the past.

Additionally it has been found that this material will not attackstainless steel, iron, copper or brass, even at high temperatures, andthis is a highly desirable attribute inasmuch, as will appear, theheat-responsive medium is confined within a bulb. tube and bellows whichmust for practical reasons be made of some metallic material.

Explaining now the particular use of the More.

mentioned material as a thermo-responsive medium in a domestic ovenautomatic temperature control device, and referring particularly toFigs. 1 and 2 of the drawings which illustrate a commercially practicalliquid type oven heat regulator, .A designates a housing to the chamberl to which fuel is delivered from a suitable source of supply through aninlet 2. Fuel is permitted to pass from the housing chamber l to alarger adjacent housing chamber 3 under the control of a valve 4 whichis normally urged towards its seat 6 by a spring 6. The chamber 3delivers fuel to the oven or other burner with which the device isassociated through its outlet 1.

Ordinarily the range is equipped with a constant burning pilot light andfuel for said pilot is delivered from the housing inlet chamber Ithrough a pilot outlet opening 8.

Those familiar with automatic oven tempera ture control are aware thatthe device being explained acts to control the delivery of fuel to theoven burner when the desired temperature within the oven has beenobtained and operate to permit the flow of fuel to said oven burneruntil said predetermined temperature is reached and will operate topermit the flow of fuel after the predetermined temperature has beenreached in the oven and then the oven temperature falls off. However itis ordinary practice not to shut off the fuel completely to the ovenburner during the use of the oven but to at all times permit a very lowfire at the burner. This is accomplished by providing a bypass and thisis designated as an entirety in Fig. 2 of the drawings at B. This bypasscomprises a bolt 9 having therein a passageway III which is incommunication with the fuel inlet chamber I through an opening H. The

passageway ID of the bolt discharges into the fuel outlet chamber 3through a suitable nozzle l2.

The regulator housing A and the parts therein can if desired bepositioned remote to the oven or other chamber the heat in which is tobe controlled but within said oven or chamber there is positioned ametallic bulb C which is connected to an expansible chamber composed ofa pair of diaphragms l3 and I 3 positioned in the housing by a tube M.

The chamber, tube and bulb are completely and entirely filled with thethermo-responsive medium and it has been found that to obtain the bestand most accurate operation the tube, bulb and chamber should beevacuated and filled with the thermo-responsive medium under a highvacuum so as to exclude all air.

As will appear, the device operates by reason of the expansion andcontraction of the thermoresponsive medium in response to thetemperature to which the bulb and tube or any portion of thethermo-responsive medium carrying parts of the device are subjected. Theoperation is limited however entirely to the expansion and contractionof the thermo-responsive medium itself and there is a complete absenceof the generation of any vapor pressure within the closed system whichcontains th thermo-responsive medium or material.

The chamber diaphragm I3 is provided with an extending pin or stud l5having attachment to a disc l6 carried in separated relationship to thebottom of a housing or carrier I! from which extends a stud or pin I8.

The disc and its housing constitute a compensator to compensate anyresponse or action of the thermo-responsive medium to heat exterior ofthe oven so as to assure that the device responds only to thetemperature within the oven or chamber within which the temperature isto be controlled. Further description of this element of the device isunnecessary as compensators are well. understood by thme familiar withinventions of the present character.

An operating shaft is has its inner end rotatably mounted within thehousing A as at and its other end carries an operating handle 2| whichwill be conveniently positioned as for instance on the front panel ofthe range. A dial 22 is associated with the operating handle and willcarry on its face temperature indications up to the maximum temperaturerange of which the device is capable of operation.

Within the fuel discharge chamber 3 of the housing a lever 23 at one endbears against the compensator stud or pin I8 and has its other endforked as at 24 to straddle a fixed stem 25 and the valve operatingsleeve 26 which is mounted for reciprocation on said fixed stem.Intermediate its length the lever is fulcrumed on a pin or stud 21carried by the inner end of the temperature setting shaft l9.

The valveoperating sleeve 26 has one end 28 engaging the valve inopposition to the spring 6 while its opposite end is provided with ahead 29 behind the forked end of the lever. Behind the sleeve head 29 acoil spring 30 having a tension greater than that of the spring 5 tendsthrough the valve sleeve to normally hold the valve in an open position.

Thus it will be seen that when the thermoresponsive fiuid within theclosed system expands it will assert a pressure upon the lever 23 torock said lever on its fulcrum 21 and move its forked end against thetension of the coil spring 30 and thus permit the valve 4 to move towardor to its seat under the tension of the coil spring 6. Reduction intemperature and the consequent contraction of the thermo-responsivemedium will permit the spring 30 to move the valve away from its seat,all as is well understood by those familiar with devices of the presentnature.

The present device provides for calibration both at the time ofmanufacture and while in use in the field. The temperature dial 22 isgeared for rotation with the operating handle 2! and these two parts areheld normally in operative engagement under the tension of the coilspring 3| which is abutted against a collar 32. To callbrate or adjustit is only necessary to push the dial inwardly and rotate it either tothe right or to the left in accord with the error to be corrected.

An elongated stop pin 33 is carried by the housing A and is in the pathof travel of an extending ear or lug 34 carried on the rear face of thedial 22. This construction will limit the permissible rotation of thetemperature setting portion of the apparatus.

Figure 5 of the drawings illustrates a conventional temperature dial andtemperature setting handle 35 and it will clearly appear that thetemperature setting handle and dial can be moved very little beyond the550 F. setting and that the Broil" setting is only slightly beyond saidhighest temperature reading. Figure 4 however which illustrates thepresent temperature setting dial 22 makes it clear that the temperaturecan be increased far beyond the 550 degree setting and that the Broilsetting is far removed from the 550 degree indication of the dial.

Where automatic ignition is used it is common practice to provide asafety valve which will cut oil the flow of fuel to the main burner inthe event the pilot light burner is not ignited and ready to ignite themain burner.

Figure 3 of the drawings illustrates a construction of this kind andhere the oven or other chamber being heated is indicated at E and theconstant burning pilot light at 36.

The principle of operation'of the safety valve is similar to theautomatic heat regulator and comprises a housing F having therein a fuelinlet chamber 31 and a fuel outlet chamber 38, communication betweenwhich is under the control of a valve 39. Fuel from some suitable sourceof supply is brought to the inlet chamber by a conduit 40 while fuelpermitted to pass to the main burner is conveyed thereto from the outletchamber 38 by a conduit 4|.

The valve 39 is normally urged towards its seat and a closed position bya spring 42. In this construction there is also provided a collapsibleand expansible chamber 43 connected by a capillary tube 44 with a bulb45 which is disposed in the oven E. The chamber, pipe and bulb arecompletely filled with the particular thermo-responsive medium ormaterial heretofore specifically described.

The bulb is closely associated with the constant burning pilot light 35and is preferably provided with a shield 41 to prevent the flame of thepilot light actually playing upon the bulb. This close associationhowever subjects the bulb to an extremely high temperature.

Within the fuel discharge chamber of the housing F a lever 38 isfulcrumed at one end upon an adjustable fulcrum pin 49 and has itsremote end 50 forked or bifurcated to straddle a fixed pin 5! upon whichis reeiprocably mounted a'valve engaging and operating sleeve 52. Oneend of this sleeve is seated Within the valve while its other end isprovided with a head 53 which is maintained in constant engagement withthe end 50 of the lever by the tension exerted by a coil spring 54. Thevalve seat appear at 55.

The expansible and contractable chamber 43 is provided with an extendingpin 56 which engages the lever 48 intermediate its ends.

With the construction thus described it will be seen that as long as thepilot burner is in operation the thermo-responsive fluid is heated andkept in an expanded condition which will cause the pin 56 of theexpanded expansible and contractable chamber43 to rock the lever uponits fulcrum and exert pressure through the valve operating sleeve 52 tohold. the valve in an open.

position.

Should the pilot'light become extinguished and the thermo-responsivemedium become cool the sprin 5 will move the valve operating sleeve andlever in a direction away from the valve and permit the spring 42 tomove the valve to a closed position and thereby prevent the delivery offuel to the main burner.

Thus it will be seen that this safety valve or device avoids thepossibility of the delivery of fuel to the main burner in the event thepilot light burner is not ignited and ready to ignite the fuel deliveredto the main burner.

It will be understood that in a gas range construction the bulb 45 andthe thermo-responsive material therein contained is subjected to theheat of the pilot light burner in addition to the heat built up in theoven by the operation of the main burner and that consequently thethermoresponsive medium must be such as to withstand temperatures ofexceedingly high degrees.

sponsive medium completely filling said bulb, conduit and chamber, saidthermo-responsive medium being tetraphenoxysilane.

2. In a thermostatically operated device for use over a wide range fromlow to high temperatures, a bulb in the zone of heat, in expansible andcontractable chamber, a conduit interconnecting the bulb and thechamber, a thermo-responsive medium confined within the closed liquidreception system formed by said bulb, conduit and chamber, saidthermo-responsive medium being tetraphenoxysilane.

ARTHUR STOCKSTROM.

